Small to medium size pleasure and commercial boats are often towed by car or truck on a boat trailer to a launch site or ramp. The boat is normally secured to the trailer by a winch and cable arrangement which engages an eye which is attached to the boat hull, most often at the bow or middle bow section of the hull. Various couplings have been devised for securing a boat to a trailer, however typically these are of complex construction and/or require an operator to operate the coupling at or in the immediate vicinity of the coupling and this can mean that when a boat is being launched into or removed from the water, the operator must enter the water to connect or disconnect the coupling between the boat and the trailer. This is inconvenient and usually leaves at least the feet and lower legs of the operator wet. Also, it usually means that during launching of a boat into the water, two persons are required, one to operate the boat and the other to release the coupling.
Various attempts have been made to relieve the need for the coupling operator to be positioned at or in the immediate vicinity of the coupling, when latching or releasing of the boat relative to the trailer is undertaken. U.S. Pat. No. 3,963,263 discloses an automatic boat trailer latch which includes two pivotable strikers that are engaged by an eye attached to the boat hull during attachment of the boat to the trailer and which pivot to create an opening through which the eye can pass. Once the eye is past the strikers, the strikers can return under the influence of springs, to a position in which release of the eye past the strikers is prevented by the strikers. Thus, the eye is captured by the strikers and the boat is secured to the trailer. To release the eye from the strikers, the strikers are manually rotated to create the opening mentioned above, to allow passage of the eye past the strikers. While the latch arrangement of U.S. Pat. No. 3,963,263 can securely capture the eye, the arrangement has several disadvantages. One disadvantage is that the boat operator is required to very precisely manoeuvre the boat to align the eye for passage past the strikers. There is because the latch has a very small point of entry so that there is very little tolerance for misalignment. This is very difficult in practice because boats move around considerably on the water during boat retrieval and boat launch angles vary considerably. Accordingly, it would be expected that the latch of this patent would result in many failed retrieval attempts.
In addition, in the captured condition of the eye within the latch, the eye is in contact with the structure of the latch and this will impose loads on the eye when the boat is being trailed, which will transfer to the boat hull. Moreover, the latch has exposed springs which can be dangerous, the overall construction appears to less robust than desirable, and there is not a simple release arrangement for release of the eye.
U.S. Pat. No. 5,193,835 discloses another form of automatic boat trailer latch which includes a spring loaded locking pin which has retracted and extended positions and which is engaged by a spring loaded blocking pin in the retracted position, to prevent the locking pin from moving to the extended position. The blocking pin is connected to a trigger which is engaged by the eye of a boat when the boat is moved onto a trailer and movement of the trigger causes the blocking pin to be shifted out of engagement with the locking pin. This releases the locking pin to the extended position through the eye, so securing the boat to the trailer. A drawback with this arrangement is the complex fabricated construction which is labour intensive to manufacture and not conducive to mass production. This arrangement also suffers from having a very small point of entry, so that it will be difficult to align the eye attached to the hull for entry into the latch. Because of this, the eye is likely to engage the latch housing during a retrieval operation and cause the housing to bend or break. Also, there is not a simple release arrangement for release of the eye.
In general, the couplings known to the applicant for the purpose discussed above are either of poor design and therefore costly and subject to a greater likelihood of failure, or are simple and less useful. Accordingly, the applicant considers it desirable to provide a boat coupling that is of relatively simple and robust construction, that is reliable and able to withstand heavy impacts that occur from time to time. The applicant also considers it desirable to provide a boat coupling that is operable remotely, so that the driver or an occupant of a vehicle to which the boat trailer is attached, or the driver or an occupant of the boat, can operate the coupling from within the vehicle or boat, preferably without having to shift either from the driver's seat of the vehicle or from the driver's position in the boat. The ability for the boat driver to release the boat remotely is particularly useful, given that the launch of a boat can then be a single person operation rather than requiring at least two persons.